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WO2008109749A9 - Détection de flux pour distribution de gaz à un patient - Google Patents

Détection de flux pour distribution de gaz à un patient Download PDF

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Publication number
WO2008109749A9
WO2008109749A9 PCT/US2008/056053 US2008056053W WO2008109749A9 WO 2008109749 A9 WO2008109749 A9 WO 2008109749A9 US 2008056053 W US2008056053 W US 2008056053W WO 2008109749 A9 WO2008109749 A9 WO 2008109749A9
Authority
WO
WIPO (PCT)
Prior art keywords
motor
impeller
torque
breathable gas
information related
Prior art date
Application number
PCT/US2008/056053
Other languages
English (en)
Other versions
WO2008109749A3 (fr
WO2008109749A2 (fr
Inventor
J Raymond Pujol
Christopher S Lucci
Original Assignee
Ric Investments Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ric Investments Llc filed Critical Ric Investments Llc
Priority to AU2008222767A priority Critical patent/AU2008222767A1/en
Priority to BRPI0808558-7A priority patent/BRPI0808558A2/pt
Priority to EP08754865A priority patent/EP2121089A2/fr
Priority to JP2009552890A priority patent/JP2010520034A/ja
Publication of WO2008109749A2 publication Critical patent/WO2008109749A2/fr
Publication of WO2008109749A3 publication Critical patent/WO2008109749A3/fr
Publication of WO2008109749A9 publication Critical patent/WO2008109749A9/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/0057—Pumps therefor
    • A61M16/0066—Blowers or centrifugal pumps
    • A61M16/0069—Blowers or centrifugal pumps the speed thereof being controlled by respiratory parameters, e.g. by inhalation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/0057—Pumps therefor
    • A61M16/0066—Blowers or centrifugal pumps
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/021—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes operated by electrical means
    • A61M16/022—Control means therefor
    • A61M16/024—Control means therefor including calculation means, e.g. using a processor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
    • A61M2016/003—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter
    • A61M2016/0033—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical
    • A61M2016/0039—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical in the inspiratory circuit

Definitions

  • the invention relates to determinations of one or more parameters of a pressurized flow of breathable gas delivered by a pressure support system to a patient.
  • a breathing disorder such as obstructive sleep apnea (OSA)
  • a pressure support device such as a continuous positive airway pressure (CPAP) device.
  • a CPAP device delivers a flow of fluid to the airway of the patient throughout the patient's breathing cycle in order to "splint" the airway, thereby preventing its collapse during sleep.
  • the term "fluid” as used herein refers to any gas, including a gas mixture or a gas with particles, such as an aerosol medication, suspended therein. Most commonly, the fluid delivered to a patient by a pressure support system is pressured air.
  • An example of such a CPAP device is the REMstar ® family of CPAP devices manufactured by Respironics, Inc. of Murrysville, Pa.
  • One aspect of the invention relates to a pressure support system that delivers a pressurized flow of breathable gas to an airway of a patient.
  • the system comprises a pressure generator, a torque monitor, a rotation monitor, and a processor.
  • the pressure generator comprises an impeller, also referred to as an impeller, and a motor.
  • the motor is configured to generate a torque.
  • the impeller is coupled to the motor such that at least a portion of the torque generated by the motor is provided to a rotor in the motor, which drives the impeller to rotate through a body of breathable gas.
  • the torque monitor is configured to determine information related to the torque generated by the motor.
  • the rotation monitor is configured to determine information related to a rotational velocity of the impeller and/or the motor.
  • the processor is configured to determine one or more parameters of the pressurized flow of breathable gas generated by the pressure generator based on the information determined by the torque monitor and the information determined by the rotation monitor.
  • the determination of the one or more parameters of the pressurized flow of breathable gas includes an adjustment for at least a portion of a difference between the torque generated by the motor and the torque that is applied to the impeller by the body of breathable gas.
  • Another aspect of the invention relates to a method of delivering a pressurized flow of breathable gas to an airway of a patient.
  • the method comprises driving an impeller with a motor, the motor being configured to generate a torque, the impeller being coupled to the motor such that at least a portion of the torque generated by the motor is provided to a rotor in the motor, which drives the impeller to rotate through a body of breathable gas.
  • the method further includes determining information related to the torque that is generated by the motor; determining information related to a rotational velocity of the impeller and/or the motor; and determining one or more parameters of the pressurized flow of breathable gas generated by the rotation of the impeller based on the information related to the torque generated by the motor and information related to the rotational velocity of the impeller and/or the motor.
  • the determination of the one or more parameters of the pressurized flow of breathable gas is made such that it includes an adjustment for at least a portion of a difference between the torque generated by the motor and the torque that is applied to the impeller by the body of breathable gas.
  • the system comprises a pressure generator, a torque monitor, a rotation monitor, and a processor.
  • the pressure generator comprises an impeller and a motor.
  • the motor is configured to generate a torque.
  • the impeller is coupled to the motor such that at least a portion of the torque generated by the motor is provided to a rotor in the motor, which drives the impeller through a body of gas.
  • the torque monitor is configured to determine information related to the torque generated by the motor.
  • the rotation monitor is configured to determine information related to a rotational velocity of the impeller and/or the motor.
  • the processor comprises a torque adjustment module, and a flow module.
  • the torque adjustment module is configured to receive information related to the torque generated by the motor from the torque monitor, to determine information related to at least a portion of a difference between the torque generated by the motor and the torque that is applied to the impeller by the body of breathable gas, and to adjust information received from the torque monitor based on the information related to the at least a portion of a difference between the torque generated by the motor and the torque that is applied to the impeller by the body of breathable gas.
  • the flow module is configured to determine a flow rate of the pressurized flow of breathable gas generated by the pressure generator based on the adjusted information related to the torque generated by the motor and the rotational velocity of the impeller and/or the motor.
  • the system comprises means for driving an impeller with a motor, the motor being configured to generate a torque, the impeller being coupled to the motor such that at least a portion of the torque generated by the motor is provided to a rotor in the motor, which drives the impeller to rotate through a body of breathable gas.
  • the impeller rotates through the body of breathable gas the gas applies a torque to the impeller, and the impeller applies a corresponding force to the gas that generates a pressurized, flow of breathable gas for delivery to a patient.
  • the system also includes means for determining information related to the torque generated by the motor; means for determining information related to a rotational velocity of the impeller and/or the motor; and means for determining one or more parameters of the pressurized flow of breathable gas generated by the rotation of the impeller based on the information related to the torque generated by the motor and information related to the rotational velocity of the impeller and/or the motor.
  • the determination of the one or more parameters of the pressurized flow of breathable gas is made such that it includes an adjustment for at least a portion of a difference between the torque generated by the motor and the torque that is applied to the impeller by the body of breathable gas.
  • FIG. 1 illustrates a pressure support system, in accordance with one or more embodiments of the invention
  • FIG. 2 illustrates a flow, current, and speed curve, according to one or more embodiments of the invention
  • FIG. 3 is a flow chart illustrating a method of delivering a pressurized flow of breathable gas to a patient, in accordance with one or more embodiments of the invention.
  • Pressure support system 10 is configured to provide a pressurized flow of breathable gas to a patient 12 according to a predetermined patient therapy algorithm.
  • pressure support system 10 is capable of determining information related to the flow rate, pressure, and/or volume of the pressurized flow of breathable gas without the need for a sensor capable of directly measuring flow, pressure, and/or volume (e.g., as is required in conventional pressure support systems).
  • a sensor capable of directly measuring flow, pressure, and/or volume (e.g., as is required in conventional pressure support systems).
  • the determination of information related to one or more of these parameters without the need for a direct measurement of any of these parameters may be made in a system that also includes one or more sensors that directly measure other ones of these parameters.
  • pressure support system 10 comprises a pressure generator 14, a patient circuit 16, a processor 18, and memory 20.
  • Pressure generator 14 is operable to generate a pressurized flow of breathable gas that is delivered to patient 12 via patient circuit 16.
  • Various aspects of the operation of pressure generator 14 may be monitored by one or more monitors (illustrated in FIG. 1 as a torque monitor 22 and a rotation monitor 24), as will be discussed later.
  • processor 18 determines info ⁇ nation related to the flow rate, pressure, and/or volume of the pressurized flow of breathable gas.
  • Processor 18 utilizes the information related to the flow rate, pressure, and/or volume of the pressurized flow of breathable gas to control pressure generator 14 such that the pressurized flow of breathable gas is delivered to patient 12 according to a predetermined patient therapy algorithm.
  • Pressure generator 14 receives fluid, such as breathing gas, from a source of breathing gas, such as ambient atmosphere or a breathing gas storage tank or system, as indicated by arrow A, and elevates the pressure of the gas at its output.
  • Pressure generator 14 includes a motor 26 and an impeller 28 coupled to the motor.
  • the impeller is coupled to the motor via a drive shaft. This coupling can be direct or indirect, e.g., through a gear assembly.
  • the present invention also contemplates coupling the impeller directly to the motor, for example by forming the impeller with or fixing the impeller to the rotor in the motor.
  • the combination of motor 26 and impeller 28 is often referred to as a blower.
  • Impeller 28 is coupled to motor 26 such that at least a portion of the torque generated by motor 26 is provided to impeller 28.
  • the torque thusly applied to impeller 28 drives the impeller to rotate through the body of breathable gas present within pressure generator 14.
  • the present invention contemplates that impeller 28 can have a variety of configurations.
  • An impeller suitable for use in the present invention is disclosed in U.S. patent no. 6,622,724, the contents of which are incorporated herein by reference.
  • the present invention further contemplates that impeller can be open or closed bladed, and can be configured to have a fan type of configuration and/or blade arrangement.
  • impeller 28 As impeller 28 rotates through the body of breathable bas, impeller 28 applies a corresponding force to the breathable gas (e.g., along arrow A), that compresses the breathable gas to generate the flow of pressurized breathable gas (e.g., indicated by arrow B). Thus, the motor applies torque on the impeller that is used to generate the pressurized flow of gas for delivery to the patient.
  • the breathable gas e.g., along arrow A
  • pressurized breathable gas e.g., indicated by arrow B
  • the torque applied to the impeller by the gas through which the impeller passes is related to items such as: (1) the fluid properties of the medium in which the impeller is immersed; (2) the flow and/or pressure conditions at the outlet and/or inlet of the blower, which are typically referred to as the "fluid load"; and (3) the blower design or configuration, such as the impeller geometry (blade shape, number, spacing, size, etc.), rotation direction of the impeller relative to the rest of the blower, and inlet and outlet geometries of the blower.
  • fluid properties include temperature, humidity, pressure, gas composition, viscosity, mass/density, etc.
  • the fluid load is "seen” as a torque by the impeller and motor.
  • the fluid load includes, for example, the patient induced pressure/flow changes at the outlet of the blower, changes in leak, or any other item that impacts pressure and flow at the outlet of the blower. All of these different torque components acting on the impeller/motor can be taken into consideration to determine one or more parameters associated with the pressurized flow of breathable gas delivered by the pressure support system to the patient, as discussed in detail below.
  • Motor 26 may include an A/C motor (e.g., single and/or poly phase induction including cage or wound rotor, synchronous machines including reluctance, wound field and permanent magnets, invariable reluctance machines including switch reluctance and stepper, etc.), or a D/C motor (e.g., a brushless motor, a coreless motor, etc.).
  • Motor 26 may be driven by a current drawn from a power source 30 (e.g., an A/C or D/C source, such as a wall socket, a battery, etc.).
  • a power source 30 e.g., an A/C or D/C source, such as a wall socket, a battery, etc.
  • the amount of current provided to motor 26 from power source 30 By controlling the amount of current provided to motor 26 from power source 30, one or more aspects of motor 26 may be controlled. For example, the torque, the rotational velocity, the rotational acceleration, and/or other aspects of the operation of motor 26 may be controlled.
  • patient circuit 16 includes a conduit 32 that carries fluid (e.g., the pressurized flow of breathable gas) from the output of pressure generator 14 to an external coupling, generally indicated at 34, on a housing 36 containing the components of pressure support system 10.
  • Housing 36 is schematically illustrated in FIG. 1 by a dashed line surrounding the components of pressure support system 10 contained in housing 36.
  • this illustration of housing 36 is not intended to be limiting. In other embodiments, more or fewer of the components of pressure support system 10 may be included within housing 36. In addition, multiple housings may be used to carry the indicated components.
  • Patient circuit 16 also includes a conduit 38 that is attached to external coupling 34 of the housing 36.
  • the patient circuit 16 in another embodiment, may alternately comprise a single conduit connected directly to the pressure generator 14 and extending to the pressure interface device 40 to be described below.
  • Conduit 38 carries the pressurized flow of breathable gas from housing 36 to an airway of patient 12.
  • a patient interface device 40 at the end of patient circuit 16 communicates the pressurized flow of breathable gas in patient circuit 16 with the airway of patient 12.
  • patient interface device 40 is any device suitable for communicating an end of patient circuit 16 with the airway of patient 12. Examples of suitable patient interface devices include a nasal mask, oral mask or mouthpiece, nasal/oral mask, nasal cannula, trachea tube, intubation tube, hood or full face mask. It is to be understood that this list of suitable interface devices is not intended to be exclusive or exhaustive.
  • patient circuit 16 is illustrated as a single-limb circuit, i.e., it has only one conduit communicating the pressurized flow of breathable gas with the airway of patient 12, it includes an exhaust element 42 to exhaust gas, such as the patient's exhaled gas, from the otherwise closed system. This flow of exhaust gas is indicated by arrow C in FIG. 1.
  • the present invention contemplates providing exhaust element 42 in patient circuit 16, on the patient interface device 40, or at both locations. Examples of conventional exhaust elements are described, for example, in U.S. Patent No. Re. 35,339 to Rapoport; U.S. Patent No. 5,937,855 to Serowski et al.; U.S. Pat. No. 6,112,745 to Lang; and published PCT application nos. WO 00/78381 to Gunaratnam et al. and WO 98/34665 to Kwok. These documents are incorporated by reference into this disclosure in their entirety.
  • a bacteria filter can be provided in or coupled to patient circuit 16.
  • a bacteria filter can be provided in or attached to the patient circuit.
  • other components such as sensors, muffler and filters can be provided at the inlet of pressure generator 14.
  • the present invention also contemplates providing a secondary flow of gas in combination with the primary flow of breathable gas.
  • a flow of oxygen from any suitable source can be provided upstream to the inlet of pressure generator 14 or downstream of pressure generator 14 (e.g., in patient circuit 16 or at patient interface device 40) to control the fraction of inspired oxygen delivered to patient 12.
  • one or more aspects of the operation of pressure generator 14 are monitored by one or more monitors.
  • the one or more monitors include a torque monitor 22 and a rotation monitor 24.
  • Torque monitor 22 monitors information related to the torque generated by motor 26.
  • the information related to the torque generated by motor 26 includes information related to current drawn by motor 26 from power source 30 (e.g., current of one leg of motor 26, current of two legs of motor 26, current of three legs of motor 26, flux, etc.).
  • Monitoring information related to the current drawn by motor 26 from power source 30 includes providing readings indicative of the amount of current being drawn at predetermined intervals (e.g., at a sampling rate). The amount of current drawn by motor 26 is related to the torque generated by motor 26.
  • Rotation monitor 24 monitors information related to the rotation of motor
  • monitors 22 and 24 may or may not include separate hardware sensors incorporated into pressure generator 14.
  • torque monitor 22 is an ammeter provided within system 10 to directly measure the current being supplied to motor 26, while in another embodiment torque monitor 22 is incorporated into a module within processor 18 that controls the supply of power to motor 26 (e.g., control module 58).
  • Processor 18 receives information related to the torque being generated by motor 26 and the rotation of motor 26 and/or impeller 28 from monitors 22 and 24, and based on this information, determines information related to the flow, pressure, and/or volume of the pressurized flow of breathable gas being delivered to patient 12. Processor 18 leverages the determined information to control pressure generator 14 to provide the pressurized flow of breathable gas according to one or more predetermined patient therapy algorithms.
  • predetermined patient therapy algorithm refers to an algorithm for delivering the pressurized flow of breathable gas to patient 12 such that one or more of the flow, pressure, and/or volume of the pressurized flow of breathable gas are varied based on one or more factors. This may include varying one or more of the flow, pressure, and/or volume of the pressurized flow of breathable gas based on the respiration of patient 12 (e.g., triggering changes based on the inspiration and/or expiration of patient 12), based on predetermined timing intervals, based on a body position of patient 12, and/or based on one or more other predetermined occurrences or triggers. As another example, one or more of the flow, pressure, and/or volume of the pressurized flow of breathable gas may be varied in order to hold another one of the flow, pressure, and/or volume substantially constant (e.g., CPAP ventilation).
  • CPAP ventilation e.g., CPAP ventilation
  • the respiratory treatment therapy i.e., the patient therapy algorithm
  • the respiratory treatment therapy involves providing a bi-level positive pressure therapy to the patient.
  • the pressure of fluid delivered to the patient's airway varies or is synchronized with the patient's breathing cycle to maximize the therapeutic effect and comfort to the patient.
  • the patent receives an inspiratory positive airway pressure (IPAP), and during expiration, the patient receives an expiratory positive airway pressure (EPAP) that is lower than the IPAP.
  • IIPAP inspiratory positive airway pressure
  • EPAP expiratory positive airway pressure
  • bi-level therapies can provide pressure waveforms having a variety of different patterns.
  • the pressure can be delivered in a traditional square wave or in a fashion that more closely mimics the pressure or flow waveform of a healthy human.
  • a respiratory treatment therapy in which the pressure provided to the patient is automatically adjusted based on the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, or snoring.
  • This respiratory treatment technique is referred to as an auto-titration type of pressure support, because the pressure support device seeks to provide a pressure to the patient that is only as high as necessary to treat the disordered breathing.
  • An example of a device that adjusts the pressure delivered to the patient based on whether or not the patient is snoring is the REMstar ® Auto device manufactured and distributed by Respironics, Inc.
  • PAV * proportional assist ventilation
  • Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient.
  • U.S. Patent Nos. 5,535,738; 5,794,615; 6,105,575; 6,609,517; and 6,932,084, (collectively referred to as "the PPAP patents") the contents of which are incorporated herein by reference, teach a pressure support device capable of operating in a PPAP mode. Examples of devices that adjust the pressure delivered to the patient based on the patient's respiratory flow is the REMstar ® Pro, Plus, or Auto with C-FlexTM or Bi-Flex devices manufactured and distributed by Respironics, Inc.
  • C-Flex refers to a device that provides a CPAP respiratory treatment therapy in which the pressure delivered to the patient is reduced in proportion to flow during expiration.
  • Bi-Flex refers to a device that provides a bi-level respiratory treatment therapy in which either the IPAP or EPAP pressures are further reduced in proportion to flow.
  • a CPAP device with C-Flex can be auto-titrating, such as REMstar ® Auto with C- FlexTM, so that the CPAP pressure varies during a treatment session based on the monitored condition of the patient.
  • a bi-level device with Bi-Flex can be auto-titrating, such as Bi-P AP ® Auto with Bi-FlexTM, so that the IPAP and EPAP pressures vary during a treatment session based on the monitored condition of the patient.
  • the difference between IPAP and EPAP which is referred to as the pressure support (PS)
  • PS the pressure support
  • predetermined patient therapy algorithms may include CPAP, bi-level ventilation, C-flex, A-flex, Bi-flex, auto-titration, proportional assist ventilation (PAV), or auto-servo ventilation or combinations thereof.
  • the predetennined patient therapy algorithm provides therapy designed to address one or more of apnea, hypopnea, flow limitation, Cheyne-Stokes respiration, and/or other respiratory phenomena.
  • Operations included in the implementation of a predetermined patient therapy algorithm may include leak estimation, inhalation/exhalation state, triggering, patient circuit pressure, leak compensation algorithms, and/or other operations.
  • Memory 20 provides an electronically readable storage medium that is operatively coupled with processor 18. This operative couple is illustrated with an arrow in FIG. 1.
  • Memory 20 may include optical readable storage media (e.g., optical disks, etc.), magnetically readable storage media (e.g., magnetic tape, magnetic hard drive, floppy drive, etc.), solid-state storage media (e.g., flash drive, etc.), and/or other electronically readable storage media.
  • Memory 20 may store software algorithms, data, and/or other information that may enable processor 18 to function properly.
  • system 10 includes a user interface 44 that provides an interface between processor 18 and an operator or patient 12. This enables information, data and/or instructions and any other communicatable items, collectively referred to as "data", to be communicated between a user and processor 18. This data may be communicated from user interface 44 to processor 18 by an operative communication link illustrated in FIG. 1 by an arrow.
  • Examples of conventional input devices suitable for inclusion in interface 44 include a keypad, buttons, switches, or keyboard.
  • Examples of conventional output devices suitable for inclusion in interface 44 include a display, lights or other visual indicia or an audio-based device, such as a speaker.
  • interface 44 it is to be understood that other communication techniques, either hardwired or wireless, are also contemplated by the present invention as interface 44.
  • the present invention contemplates providing a smart card terminal that enables data to be loaded into processor 18 from the smart card or loaded onto the smart card from the processor 18.
  • Other exemplary interface devices and techniques adapted for use with the pressure support system 10 include, but are not limited to, an RS-232 port, CD reader/writer, DVD reader/writer, RF link, an IR link, modem (telephone, cable or other).
  • any technique for providing, receiving, or exchanging data with processor 18 are contemplated by the present invention as interface 44.
  • processor 18 is shown in FIG. 1 as a single entity, this is for illustrative purposes only.
  • processor 18 may include a plurality of processing units. These processing units may be physically located within the same device (e.g., within housing 36 of system 10), or processor 18 may represent processing functionality of a plurality of devices operating in coordination. In instances in which a plurality of devices are implemented, operative communications links may be formed between the devices to enable communication and coordination therebetween.
  • processor 18 may include one or more processors external to the other components of system 10 (e.g., a host computer), one or more processors that are included integrally in one or more of the components of system 10 (e.g., one or more processors included integrally within housing 36, etc.), or both.
  • processors external to other components within system 10 may, in some cases, provide redundant processing to the processors that are integrated with components in system 10, and/or the external processor(s) may provide additional processing to determine additional information related to the operation of system 10 and/or the pressurized flow of breathable gas delivered to patient 12.
  • processor 18 includes a torque adjustment module 46, a flow module 50, a pressure module 52, a volume module 54, a therapy module 56, and a control module 58.
  • Modules 46, 50, 52, 54, 56, and/or 58 may be implemented in software, hardware, firmware, some combination of software, hardware, and/or firmware, and/or otherwise implemented. It should be appreciated that although modules 46, 50, 52, 54, 56, and/or 58 are illustrated in FIG.
  • processor 18 includes multiple processing units modules 46, 50, 52, 54, 56, and/or 58 may be located remotely from the other modules and operative communication between modules 46, 50, 52, 54, 56, and/or 58 may be achieved via one or more communication links.
  • Such communication links may be wireless or hard wired.
  • Torque adjustment module 46 adjusts information related to the torque generated by motor 26 that is provided by torque monitor 22. For example, in one embodiment, torque adjustment module 46 adjusts readings of current being drawn by motor 26 that are provided by torque monitor 22. As was mentioned above, the amount of current drawn by motor 26 is related to the torque generated by motor 26. This relationship may be expressed as:
  • T represents the torque generated by motor 26
  • K T is related to the motor torque sensitivity constant
  • I represents the current drawn by motor 26 from power source 30.
  • the relationship expressed in equation (1) may be leveraged to determine a total amount of torque generated by motor 26 based on the total current drawn by motor 26.
  • the parameters (e.g., flow rate, pressure, volume, etc.) of the pressurized flow of breathable gas may not be determined similarly (based on the total torque generated by motor 26) because not all of the torque generated by motor 26 is transferred to impeller 28 and/or to the pressurized flow of breathable gas.
  • the adjustment of current readings and/or other metrics related to the torque generated by motor 26 made by torque adjustment module 46 enables enhanced determinations of one or more parameters of the pressurized flow of breathable gas from the information provided by torque monitor 22.
  • T mo tor represents the total torque generated by motor 26
  • Tn ow represents the torque applied to impeller 28 by the flow of breathable gas as impeller 28 rotates through the gas (e.g., that corresponds to the compressive force that pressu ⁇ zes the gas)
  • T winc i age represents the torque experienced by motor 26 due to windage created internally within motor 26
  • T fnct i On represents the torque dissipated due to friction/stiction in the motor 26/impeller 28 system
  • T acce i eratlon represents torque used to change the rotational velocity of impeller 28 (e.g., due to inertia)
  • T oth e r represents the torque dissipated by one or more other torsions experienced by the motor26/impeller 28 system.
  • T other includes, for example, torques acting on impeller 28 such as: (1) the fluid properties of the medium in which the impeller is immersed; and (2) the blower design or configuration.
  • I tota i represents the total current drawn by motor 26
  • I flow represents the current drawn by motor 26 to generate the portion of T f j ow
  • Iw mdage represents the current drawn by motor 26 to generate a torque equal and opposite to T wm d ag e
  • It ⁇ ction represents the current drawn by motor 26 to generate a torque equal and opposite to Ta ct i on
  • I a cceie r atio n represents the current drawn by motor 26 to generate a torque equal and opposite to Tacceieratio n
  • I ot her represents the current drawn by motor 26 to generate a torque equal and opposite to T o ther-
  • torque adjustment module 46 adjusts the information so that the adjusted information will more accurately correspond to the torque that is applied to the impeller by the breathable gas.
  • the torque monitor 22 provides information related to the current drawn by motor 26
  • the adjusted measurement of current will more closely reflect the component of the current that corresponds to the torque component associated with the compression of the pressurized flow of breathable gas by the rotation of impeller 28, or T flow (this current component is represented by I flow in equation(3)).
  • torque adjustment module 46 determines one or more of the current components drawn by motor 26 that correspond to at least a portion of the difference between the total amount of torque generated by motor 26, T mo to r5 and the torque applied by the breathable gas to impeller 28, T flow .
  • these current components may include Iw m dage, Wio n , Iacceieration, etc.
  • Torque adjustment module 46 then adjusts the readings of I tota i provided by torque monitor 22 by removing the superfluous current components that have been determined (e.g., by subtracting Iwmdage, taction, and/or I aC DCeration from Itotai).
  • T acce i erat i on may also be written as:
  • Torque adjustment module 46 leverages this relationship between ⁇ and
  • Iacceieration to determine Iacceieration from a measurement or estimation of ⁇ .
  • K T and J m may be known (e.g., via calibration, programmed at manufacture, etc.) and torque adjustment module 46 may determine Iacceieration according to equation (7) based on a measured or estimated ⁇ .
  • I acc ei era tio n as a function of ⁇ may be determined empirically for a plurality of different ⁇ , and the results may be stored in a lookup table that is accessed by torque adjustment module 46 to determine Iacceie r atio n based on a measured or estimated ⁇ .
  • ⁇ is not directly measured.
  • system 10 includes only a monitor of the rotational velocity of impeller 28, and not its rotational acceleration.
  • a rotational acceleration monitor that monitors the rotational acceleration of impeller 28 directly and provide readings of the rotational acceleration of impeller 28 to torque adjustment module 46 (e.g., at predetermined intervals).
  • torque adjustment module 46 e.g., at predetermined intervals.
  • an approximation or estimation of the instantaneous ⁇ of impeller 28 may be determined by torque adjustment module 46 based on readings of the rotational velocity of impeller 28 provided by rotation monitor 24.
  • the difference between two of the readings of rotational velocity may be used as a measurement of ⁇ (e.g., ⁇ t _ x - ⁇ t ⁇ a , where ⁇ t represents rotational velocity at time t and ⁇ t _i represents the rotational velocity at time t-1).
  • two or more measurements of ⁇ that have been made based on temporally proximate pairs of readings of rotational velocity may be averaged to determine a value representative of ⁇ of impeller 28.
  • determining a closed loop estimate of ⁇ may include comparing the rotational velocity of the motor 26/impeller 28 system to the time integral of an estimation of ⁇ (e.g., made according to one of the methods described above) to further refine the estimation of ⁇ .
  • torque adjustment module 46 determines -acc el e r atio n ( e -g- > as described above), or a corresponding component of some other metric of torque, and adjusts I tota i, or a corresponding component of some other metric of torque, accordingly.
  • this embodiment is not intended to be limiting, and that in other embodiments, one or both of Iwindage and If ⁇ ction, or corresponding components of some other metric of torque, may similarly be determined and adjusted for.
  • torque adjustment module 46 may subtract the value determined for Iacceie r atio n by torque adjustment module 46 from amount of the total current, I tota i, indicated in a corresponding reading provided by torque monitor 22. This adjustment enables torque adjustment module 46 to provide an adjusted current that is approximately equal to the component of the current drawn by motor 26 that corresponds to the compressive force provided by impeller 28 to the pressurized flow of breathable gas, or I fl0W .
  • Flow module 50 is configured to determine a flow rate of the pressurized flow of breathable gas generated by the rotation of impeller 28. Flow module 50 determines the flow rate based on the principle that the flow rate of the flow of breathable gas is a function of the rotational velocity of impeller 28 and the compressive force that is applied to the gas by impeller 28 (e.g., the force applied to the gas by impeller 28 that corresponds to T flow ).
  • flow module 50 leverages the relationship between T flow and I flow (illustrated above in equation (I)) and the measurements of rotational velocity provided by rotation monitor 24 to determine the flow rate of the pressurized flow of breathable gas based on the measurements of rotational velocity and adjusted measurements of current drawn by motor 26 from power source 30 (e.g., determinations of I fl0W ) provided by current adjustment module 46.
  • flow module 50 includes a representation of an empirically predetermined current, velocity, and flow curve that returns a flow rate of the pressurized flow of breathable gas as a function of a measurement of rotational velocity of impeller 28 and an adjusted measurement of current (e.g., a detennination of I ⁇ Ow )-
  • the representation of the current, velocity, and flow curve may include a lookup table including values from the predetermined curve, a mathematical model of the predetermined curve, and/or other representations of a three variable function or curve.
  • FIG. 2 illustrates a current, velocity, and flow curve.
  • pressure module 52 is configured to determine a pressure of the pressurized flow of breathable gas generated by the rotation of impeller 28. In one embodiment, pressure module 52 determines the pressure of the flow of breathable gas based on the flow rate of the gas (e.g., as determined by flow module 50). In determining the pressure of the flow of breathable gas based on the flow rate of the gas, pressure module 52 takes into account various variables of patient circuit 16.
  • the variables of patient circuit 16 that are accounted for by pressure module 52 may include one or more of a circuit cross-section, a circuit path length, a geometry of an opening in patient circuit 16 (e.g., a size, a shape, etc.), a position on patient circuit 16 of an opening, one or more aspects of patient interface device 40, and/or other variables of patient circuit 16. It should be appreciated that first determining the flow rate of the pressurized flow of breathable gas, and then determining the pressure of the flow of breathable gas based on this flow rate, as described herein with respect to system 10, is not intended to be limiting.
  • pressure module 52 may determine the pressure of the flow of breathable gas directly from measurements of the rotational velocity of impeller 28 and adjusted measurements of the torque generated by motor 26 (or a related metric) using a predetermined curve (e.g., as described above with respect to flow module 50 using a predetermined flow, velocity, and current curve).
  • Volume module 54 is configured to determine a volumetric measurement of the pressurized flow of breathable gas generated by the rotation of impeller 28. In one embodiment, volume module 54 determines a volumetric measurement of the flow of breathable gas based on the flow rate of the gas (e.g., as determined by flow module 50). It should be appreciated, however, that first determining the flow rate of the pressurized flow of breathable gas, and then determining a volumetric measurement of the flow of breathable gas based on this flow rate, as described herein with respect to system 10, is not intended to be limiting.
  • volume module 54 may determine a volumetric measurement of the flow of breathable gas directly from measurements of the rotational velocity of impeller 28 and adjusted measurements of the torque generated by motor 26 (or a corresponding metric) using a predetermined curve (e.g., as described above with respect to flow module 50 using a predetermined flow, velocity, and current curve).
  • a predetermined curve e.g., as described above with respect to flow module 50 using a predetermined flow, velocity, and current curve.
  • Therapy module 56 analyzes the parameters of the pressurized flow of breathable gas determined by one or more of flow module 50, pressure module 52, and/or volume module 54 to ensure that the flow of breathable gas is provided to patient 12 according to a predetermined patient therapy algorithm.
  • therapy module 56 may analyze the relevant parameter(s) to determine information related to the respiration of patient 12 (e.g., the beginning and/or end of inspiration and/or expiration by patient 12, a respiratory event, the timing of respiration, other information related to the respiration of patient 12, etc.) and/or compare current levels of one or more of the measured parameters to desired levels of the one or more measured parameters.
  • therapy module 56 determines adjustments that should be made in order to ensure that the flow of breathable gas is delivered in the appropriate manner.
  • therapy module 58 may determine that the flow rate and/or pressure of the flow of gas should be increased or decreased dynamically based on the breathing patterns of patient 12, the body position of patient 12, and/or other phenomena.
  • the predetermined patient therapy algorithm may include CPAP, bi-level, C-flex, A-flex, bi-flex, auto-titration, proportional assist ventilation positive airway pressure therapy, or auto-servo ventilation.
  • the predetermined patient therapy algorithm provides therapy designed to address one or more of apnea, hypopnca, flow limitation, Cheyne-Stokes respiration, and/or other respiratory phenomena.
  • Operations included in the implementation of a predetermined patient therapy algorithm by therapy module 56 may include leak estimation, inhalation/exhalation state, triggering, patient circuit pressure, leak compensation algorithms, and/or other operations.
  • Control module 58 controls pressure generator 14 to provide the pressurized flow of breathable gas to patient 12 according to a predetermined patient therapy algorithm. In one embodiment, this includes controlling pressure generator 14 to provide adjustments to the flow rate, pressure, and/or volume of the pressurized flow of breathable gas that are relayed to control module 58 from therapy module 56 (e.g., determined as described above). The control module 58 controls the pressure generator 14 to provide the appropriate increases or decreases in the flow rate, pressure, and/or volume of the flow of breathable gas by, for example, controlling the amount of torque generated by motor 26 to increase or decrease the rotational velocity of impeller 28.
  • FIG. 3 includes a flow chart that illustrates a method 60 of delivering a pressurized flow of breathable gas to an airway of a patient, in accordance with one embodiment of the invention. It should be appreciated that although specific reference is made below regarding various operations of method 60 that can be executed by components of system 10 (e.g., illustrated in FIG. 1 and described above), this is for illustrative purposes only. In other embodiments, systems other than system 10 may be implemented to execute some or all of the operations of method 60.
  • Method 60 includes an operation 62, at which a motor generates a torque that drives the impeller to rotate through a body of breathable gas.
  • a motor generates a torque that drives the impeller to rotate through a body of breathable gas.
  • the gas applies a torque to the impeller, and the impeller applies a corresponding compressive force to the body of breathable gas that generates a pressurized flow of breathable gas for delivery to the patient.
  • the motor is driven by a current drawn from a power supply.
  • the motor may include a motor similar to motor 26 (e.g., illustrated in FIG. 1 and described above) and the impeller may include an impeller similar to impeller 28 (e.g., illustrated in FIG. 1 and described above).
  • operation 64 information related to the rotational velocity of the motor/impeller system may be determined. This may include providing periodic readings of the rotational velocity of the motor/impeller system. In one embodiment, operation 64 may be executed by a rotation monitor similar to rotation monitor 24 (e.g., illustrated in FIG. 1 and described above).
  • information related to the torque being generated by the motor may be determined. This may include providing periodic readings of one or more metrics indicative of the amount of torque being generated by the motor (e.g., current, flux, force, torque, etc.). It should be noted that measuring flux includes measuring winding flux and/or magnet flux within the motor or external to the motor. If current is the monitored metric, it is to be understood that the current can be monitored in any one of a variety of ways, such as galvanic or flux based current measurement techniques. In one embodiment, operation 66 may be performed by a torque monitor similar to torque monitor 22 (e.g., illustrated in FIG. 1 and described above).
  • a reading indicative of the torque being generated by the motor may be adjusted to account for at least a portion of a difference between the torque generated by the motor and the torque applied to the impeller by the breathable gas.
  • This difference may include one or more of a portion of the differences caused by friction in the motor/impeller system, a portion of the difference caused by windage, a portion of the difference caused by acceleration and/or deceleration of the rotational velocity of the impeller, and/or other torques experienced by the motor/impeller system.
  • operation 68 includes (i) determining a component of the information related to the at least a portion of the difference between the torque generated by the motor and the torque applied to the impeller by the body of breathable gas and (ii) adjusting a reading of the information related to the total amount of torque generated by the motor by subtracting the determined component of the information related to at least a portion of the difference between the torque generated by the motor and the torque applied to the impeller by the body of breathable gas from the information related to the total amount of torque generated by the motor.
  • operation 68 is executed by a torque adjustment module similar to torque adjustment module 46 (e.g., shown in FIG. 1 and described above).
  • operation 70 one or more parameters of the pressurized flow of breathable gas are determined based on the information related to the adjusted torque determined at operation 68. Accordingly, the one or more parameters of the pressurized flow of breathable gas determined at operation 70 reflect an adjustment for at least a portion of the difference between the torque generated by the motor and the torque applied to the impeller by the body of breathable gas.
  • operation 70 includes the determination of one or more of a flow rate, a pressure, and/or a volume of the pressurized flow of breathable gas based on the adjusted information related to the torque generated by the motor and information related to the rotational velocity of the impeller (e.g., provided by operation 64).
  • operation 70 is executed by one or more of a flow module, a pressure module, and/or a volume module similar to flow module 50, pressure module 52, and/or volume module 54 (e.g., shown in FIG. 1 and described above).
  • the pressurized flow of breathable gas may be delivered according to a predetermined patient therapy algorithm.
  • an adjustment of one or more parameters of the pressurized flow of breathable gas may be determined according to a predetermined patient therapy algorithm
  • an adjustment of one or more aspects of operation of the motor/impeller system e.g., torque, rotational velocity, etc.
  • the adjustment of the one or more aspects of operation of the motor/impeller system determined at operation 74 may then be implemented in operation 62.
  • operations 72 and 74 may be executed by a therapy module and a control module, respectively, similar to therapy module 56 and control module 58, respectively (e.g., shown in FIG. 1 and described above).

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  • Health & Medical Sciences (AREA)
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  • Pulmonology (AREA)
  • Engineering & Computer Science (AREA)
  • Anesthesiology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Hematology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Abstract

L'invention concerne un système de support de pression (10) qui distribue un flux de gaz aux voies respiratoires d'un patient. Le système comprend un générateur de pression (14), un contrôleur de couple (22), un moniteur de rotation (24) et un processeur (18). Le générateur de pression comprend un impulseur (28) et un moteur (26). L'impulseur est couplé au moteur de sorte qu'au moins une partie du couple généré par le moteur est fournie à l'impulseur. Lorsque l'impulseur tourne à travers le corps de gaz respirable, le gaz applique un couple à l'impulseur, et l'impulseur applique une force au gaz générant le flux de gaz. Le moniteur de couple détermine des informations liées au couple généré par le moteur. Le moniteur de rotation détermine des informations liées à la vitesse de rotation de l'impulseur et/ou du moteur. Le processeur détermine un ou plusieurs paramètres du flux de gaz en fonction des informations déterminées par les moniteurs de couple et de rotation.
PCT/US2008/056053 2007-03-07 2008-03-06 Détection de flux pour distribution de gaz à un patient WO2008109749A2 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU2008222767A AU2008222767A1 (en) 2007-03-07 2008-03-06 Flow sensing for gas delivery to a patient
BRPI0808558-7A BRPI0808558A2 (pt) 2007-03-07 2008-03-06 Sistema de suporte de pressão, e, método para dispensar um escoamento pressurizado de gás respirável para via aérea de um paciente.
EP08754865A EP2121089A2 (fr) 2007-03-07 2008-03-06 Détection de flux pour distribution de gaz à un patient
JP2009552890A JP2010520034A (ja) 2007-03-07 2008-03-06 患者への気体供給のための流動センシング

Applications Claiming Priority (4)

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US90534007P 2007-03-07 2007-03-07
US60/905,340 2007-03-07
US12/040,043 2008-02-29
US12/040,043 US20080216833A1 (en) 2007-03-07 2008-02-29 Flow Sensing for Gas Delivery to a Patient

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WO2008109749A2 WO2008109749A2 (fr) 2008-09-12
WO2008109749A3 WO2008109749A3 (fr) 2008-12-04
WO2008109749A9 true WO2008109749A9 (fr) 2009-01-22

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EP2121089A2 (fr) 2009-11-25
WO2008109749A3 (fr) 2008-12-04
WO2008109749A2 (fr) 2008-09-12
AU2008222767A1 (en) 2008-09-12
US20080216833A1 (en) 2008-09-11
JP2010520034A (ja) 2010-06-10
BRPI0808558A2 (pt) 2014-08-19

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